Interface strain coupling and its impact on the transport and magnetic properties of LaMnO3 thin films grown on ferroelectrically active substrates

► Strong interface strain coupling in LaMnO3/PMN-PT heterostructure. ► In situ dynamic turning of the strain and lattice distortion of LaMnO3 films. ► Coupling of electrons to lattice strain is crucial to understand the strain effect. Thin films of LaMnO3 have been epitaxially grown on 〈001〉 oriented ferroelectric 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) single-crystal substrates. The poling of the PMN-PT crystal causes a decrease in the resistance and an increase in the magnetization and magnetoresistance of the LaMnO3 film. In situ X-ray diffraction measurements revealed that these changes arise from the poling-induced strain in the PMN-PT substrate, which reduces the in-plane tensile strain and the Jahn–Teller (JT) distortion of MnO6 octahedra of the LaMnO3 film. Moreover, it was found that the transport properties of LaMnO3 films are much more sensitive to the poling-induced strain than that of CaMnO3 films for which there is no JT distortion, implying that the electron–lattice coupling is one of the most important ingredients in understanding the strain effect in LaMnO3 films.